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fairly newish Stemme S12 (83'wing span self luanch glider) propelled by a Rotax turbo charged 914.  100hours so far on the engine and not making 100% of the orginal RPM currenttly only making 5300 at max throttle setting ,remembreing uppward of 6200-6400  a couple of years back when new . After a 5-10 minute climb to 3-4000'  5300 rpm I will see a red lite on the manifold pressure ( assuming it is a high pressure indication) pulling the throttle back a tad (loose 100rpm or so) seems to cure the lite (turns off),  We've used only 100LL . Any suggestions to get the power back to normal would be great. 

  • Re: red light manifold pressure ?

    by » 3 months ago


    Hi Gary,

    hoping that this engine was not used in the rev-range you remember. Constant max rev is 5500. 5800 is limited to 5min only. 5300 seems OK though. However, moving towards 5500 would allow you to use the capabilities of your engine better.

    MAP issue seems weird. With a non-turbo you would see lower MAP the higher you climb. Cheching the parameters (setup) for the red light to come up and the waste gate bowdencable may be worthwhile to start with.


    Thank you said by: Gary Davis

  • Re: red light manifold pressure ?

    by » 3 months ago


    As Peter said, 6200-6400 is far outside the maximum rpm limit of 5800 (5 minutes only).

     

    Are you sure that the light is for high manifold pressure and not one of the two indicator lights that is connected to the turbo control unit (TCU)?

     

    The behavior you describe (comes on after 5 minutes and goes out with throttle reduction) would be consistent with the caution light for the turbo. You can check this by watching the light when power is first applied to the TCU. If it is the TCU warning light, it should come on for a few seconds and then go out.

     


  • Re: red light manifold pressure ?

    by » 3 months ago


    If you don't have the AFM for your Stemme, please go to Stemme's website and download it.

     

    Here is the pertinent section:

     

    3.9.4.3 RED WARNING LIGHT FOR MANIFOLD PRESSURE STEADY ON OR FLASHING

    RED WARNING LIGHT FOR MANIFOLD PRESSURE STEADY ON

    Maximum allowed manifold pressure has been exceeded; procedure:

    • Manifold Pressure (MAP) is not automatically controlled.

    • Throttle                      REDUCE

    • RPM and MAP          CONTROL with throttle (red warning light must extinguish)

    • RPM setting              <4500 RPM rercommended

    • Limited engine power range has to be expected, manifold pressure control is not operating properly.

    NOTICE

    The exceedance of maximum allowed engine limits must be documented in the aircraft-logbook with details including nature of incident, date, duration and the degree of exceedance.

    RED WARNING LIGHT FOR MANIFOLD PRESSURE FLASHING

    T/O-power has been set for more than 5 minutes, procedure:

    • Throttle REDUCE to max. continuous power or less.

    CAUTION

    The manifold pressure is not automatically limited or reduced.

    NOTICE

    The exceedance of the 5 minute takeoff power limitation must be documented in the aircraft-logbook with date and duration of exceedance.

     

    Mike


    Thank you said by: Gary Davis, Bill Hertzel

  • Re: red light manifold pressure ?

    by » one month ago


    thanks for your correct reply!!! the door lever is not free as  should be, I shot some mouse's milk (lube) but is is an up hill for the lube to do the work , the waste gate shaft is on the bottom on the Stemme no good way for any lube to creep up. Guessing  further disassembly to further service the waste gate door ?


  • Re: red light manifold pressure ?

    by » one month ago


    Call Rick Wright in Tucson, Az. He's the Stemme expert along with 914's

    520-471-9328.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


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